79 marathon issues

[drek67055]

Just picked her up a few weeks ago rebuilt the top end due to low compression. got it all put back together correctly including the ringsstart out at 125 psi starts right up has no power butbut the muffler and half knocked out some of the baffles and ones that were broken removed already burnt it gained some power back (had all the power it needs with the muffler removed). Works great in reverse (always easier to pull then push) but almost gutless going fwd. Thought it was gtg until I added another person then had no power to move forward. What else could it be? Fuel pump squirts like a champ and choking it even part way does nothing except try to kill it. Fires right up with no issues.